Method for forming a gasket



oct. 17, 1961 H. E. STOVER 3,004,297

' METHOD F'OR FORMING A GASKET y l Filed Aug. 12, 1958 ,i I' n u) 17T' 1%' 15 u \\\\\\*'\\\&m XN v u I3 L3 1 l 2 1 'LL VicT 1 5 2 1 13 8/ ,e lg l e l n' ,32" l54 L1 l 5 V\ ,x "L 2. 3 a. El. 7 3 AL H f. S orf BY 4Q/ey r e y Y 3,004,297 p, METHOD FOR FORMING A GASKET Harry' E. Stover, Lancaster, Ohio, assignor to Anchor Hocking Glass Corporation, Lancaster, Ghia, a corpo'- Aratitni of Delaware Filed Aug. 12, 1958, Ser. No. 754,658 4 Claims. (Cl. 18-59) The present invention relates to a method for forming a gasket and more particularly to the method for molding a gasket within a closure from a gasket blank inserted in the closure. j

, The increasing use `of food products which are preferably packaged in hermetically sealed containers presents a vcontinually growing demand for improved sealing closures which are easily and inexpensively manufactured. Such closures are provided with sealing gaskets made of rubber or other suitable sealing material. Where a savingis effected in the manufacture and application of the sealing gasket, the cost of manufacturing the closure is signicantly reduced.

j A preferred embodiment of the present invention illustrates moldinga gasket in a closure of the type disclosed in the Harry E. Stover United States patent application Serial No. 687,035, filed September 30, 1957, and owned by the assignee hereof. It will be understood that the invention is not limited to this particular type of closure but is also applicable to other types of closures.

There are presently several methods of applying gaskets to closures. One such method comprises cutting a gasket from a vulcanized tube of sealing material and assembling the cut gasket into the closure.

VAnothermethod of applying a gasket to a closure comprises placing a slug of gasket material on the inside of a closure and thereafter utilizing a suitable die for shaping the gasket material into a gasket.

Another method of forming the gasket comprises cutting a ring from a slug or block of gasket material, placingthe cut ring into a closure and applying pressure to the cut ring by a suitable die to shape the cut ring Within the closure.

' The present invention is an improvement over these methods andhas for one of its objects the provision of an improved method for forming gaskets.

` Another object of the present invention is to provide an improved method of forming a gasket which forms and separates a ring of gasket material from a gasket blank while simultaneously molding the ring of gasket material into ,shape so that the remaining gasket material may be removed and re-used.

A'Another object of the present invention is to provide an' improved method of forming a gasket which will simultaneously form and separate a zone of gasket material from a gasket blank, shape the separated zone, and form an annular groove therein.

Other and further objects of thev invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention inpractice.

A preferred embodiment of the invention has been chosen forpurposes of illustration and description and is Y 3,004,297 Patented Oct. 17, 1961 FIG. 2 is a view vsimilar to FIG. 1 showing the initial position of the molding punch as it is being pressed into the gasket blank to force some of the gasket material to' ward the skirt portion of the closure;

` FIG. 3 shows the molding punch in a more advanced position forming and separating a peripheral zone from the gasket-blank and forcing more of the gasket materia toward the skirt portion of the closure;

FIG. 4 shows the molding punch in its fully depressed position separating a peripheral ring of gasket material from the main gasket blank and simultaneously pressing the separated ring into shape;

FIG. 5 is a sectional view showing the remaining gasket connected to the formed gasket by a thin annular zone of rubber;

FIG. 6 is an exaggerated detailed view showing the action of the central portion of the gasket material in drawing away to sever the molded gasket ring from the remainder of the gasket blank; and

FIG. 7 is a sectional view of a closure showing the position of the remaining gasket blank after it has fully drawn itself aWay from the formed gasket.

Referring more particularly to FIG. l, a cup-shaped closure lis shown having a cover portion 3 and a depending Iskirt portion 4. The cover portion 3 is provided With a gasket-receiving channel 5 and the skirt portion 3 has an extending iiared portion 6 with its edge 7 turned partially Vinwardly to form an inwardly directed flange 7'.

The cup-shaped closure 1 may be shaped into the desired form by iirst stamping the cup-shaped closure from a sheet of tin-plate or other suitable metal, coated with a suitable lacquer, and thereafter turning the edge of the skirt portion 4 inwardly to form the ilange A gasket blank 10 is placed inside the closure shell 1 on the cover portion 3. The diameter of the gasket blank lil is preferably smaller than the diameter of a cavity 12 in the molding punch 1l to facilitate registry with it and the gasket blank l() is slightly thicker than the depth of the cavity 12 so that when the punch 11 is lowered the gasket blank 1t) will be received within cavity l2 and the upper wall l2' of the cavity 12 will strike the gasket blank and will force the gasket material into a suitable gasketforming position (FIGS. Zand 3). The gasket blank 10 v may be a rubber compound, a synthetic com-pound, or any other suitable sealing material.

The closure shell 1 with the gasket blank 'itl therein is placed in a support member 2 positioned beneath the reciprocable molding punch 11 carrying a resiliently mounted sleeve 2 which is adapted to strike when the molding punch 11 is lowered on the support member 2 to form a tight seal. The molding punch 11 is provided with a projecting circumferential separating and shaping portion 13 adapted to cooperate with cavity 12 to force a portion of the gasket blank 10 into a peripheral ring to space or separate the formed ring from the gasket blank 10, and to shape the ring into a gasket Z0 (FIG. 7).

The projecting,.circumferential vseparating andfshaping.

portion 13 is provided with a separating, spacing, pinching or thinning surface 1'3, a horizontal shaping surface 14 and a vertical shaping surface 15. The vertical shaping surface 15 has a thickened portion 16 which is adapted to strike the inwardly extending flange '7' of the skirt 4 and to curl it into a bead 8 (FIG. 2). When the molding punch 11 is in its molding position (FIGS. 4 and 5) the thickened portion 16 also forms a tight seal with the open vbead d to permit the gasket material to iiow into the open bead while preventing any of the gasket material from escaping fromV between the bead y8 andthe punch 11.

lf desired, the separating and shaping portion 13 of the molding punch 11 may be provided with a groove-forming extension 17 to form an annular groove .13 (FIG. 7) in the gasket. While the groove-forming extension 17 is illustrated in the drawings as being located at the outer edge of the horizontal vshaping.portion 14,it will be under stood 'that the .annular groove 1S maybe eliminated, if

desired, or it may be located-at other positions, as desired, in which case the location of the grooveeforrning extension 17' will be changed accordingly...

The operation of the preferred embodiment is shown inr FIGS. 2 to 6. The sealing ring 2 is iirstV moved down- Wardiy into position against the support 2 sothat a ring gasket 2,3 forms an air-tight seal permitting the evacuation of air from the molding chamberwhere `itlis. desired to do so.

The molding punch 11 is now moved downwardly until the upper wall 12 of Vthe cavity 12 Aengages the gasket blank 16 and begins to depress it (FIG.` 2). Since rubber oirubberflike gasket materials .are incompressible, the gasket material is forced to flow into Athe .gasket-receiving channel to form the peripheral. ring or `zone ,19 (HG. 3). As the punch 11 is depressed further the vgasket material continues to iiow under spacing orA separating surface 13', the horizontal shaping surface 14 and alongthe vertical shaping surface 15 to forma peripheral zone 419. The pressure of the upper Wall12. on the gasket blank 1 0-tends to stretch the rubber as itforces the rubber into the gasket-receiving channel 5 of the closure cap. v Y

As the molding punch 11 is lowered to its lowermost position (FIG. 4), the upper Wall12 of the cavity 12 will have forced the rubber along the entire vertical shaping surface 15 and into the open bead 3 and will have forced the rubber to conform to the shape of the shaping surfaces 14 and 15. The rubber will alsoow around the groove-forming extension 17 to simultaneously form the annular groove 18. The fact that the thickened portion of the vertical shaping surface 16 of the molding punch 11 forms a tight seal with the bead S of the closure prevents any of the: gasket material fromscapinglFlGS. 3 and 4).

The peripheral zone 19 is connected .to the remaining gasket blank by a thin strip of rubber 25 beneath the spacing or separating surface .13. (FIG-4). Since the gasket blank iti has been stretched or deformed during the preceding operations the memory characteristicsy of the remaining portions of the gasket blank 10` will `cause it to contract when free todo so. Since the connecting strip of rubber 25 is very thin, thiscontracting action will tear or rupture the strip 25 and will separate the molded gasket 2t) from the remaining gasket blank 11i'. This action is illustrated in FG. 6 where the strip of rubber 2S is shown drawn away from the formed gasket 2S* and severed by the contracting action.

It will be noted that the punch .11 does not touch the metal of the cap. This prevents the coating of the cap from being scratched or marred and thereby prevents the metal from rusting.

After the rubber has contracted to sever the connecting strip 2.5, the remaining portion 10' of thegasket blank 10 can be removed from the closure for re-use inthe manufacture of additional gasket blanks.

The portion of the `undersideof the-cover of the closure registering with the cavityr12 of the shaping punch is pref- V erably coated with a suitable compound 22 which will prevent the sealing compound pressed against it from bonding to it and to facilitate the easy removal of the excess compound. lt is preferred that a silicone cornpound be used for this purpose but it Will Ybe understood that other compounds will serve this purpose. The lacquer tends to bond the gasket portion to the metal but, if desired, a bonding material may be applied to the inside of the skirt of the cap and to the peripheral portion of the cover above the basket. After the gasket 20 is completely shaped and the vcenter portion removed, the gasket within the closurev maybe Acure'dby.placing the closure in an ove'n to vulcanize or partially vulcanize the sealing compound.v If an-unvulcani'zed orv plastic type gasket is desired, the curing may be dispensed with.

While the separatingl'edge' 13 ofthe punch has been illustrated as flat in the preferredembodiment to leave athin annular zone-.of rubber v2 5 between 'the gasketl and the` center blanlg-it willbe .understood that thewidth may bedecreased if desired-orl a roundedannularbead or rib may be formed on the surface to facilitate the 'ber .material to be easily removed for re-usein forming additional gaskets. Since the molding punch does not touch the metal of the cap, .the lacquer coating of the cap will'not marred and `thuswill prevent;v the formation of rust. K

As .various changes may be made in the form, confv struction and arrangement ofthe partsfand in the stepsv herein without departing from the spiritIandgscope of theinvention and Without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not ina limitingA sense.V

Having thus described my invention, lI claim:

l. The method of molding a sealing gasket in a closure cap, Whichfcomprises coating the inside cover of said closure with a silicone compound, placing arrgasketblank on the inside of said closure, applying pressure to com-V press the gasket blank andfto kforce-ia portion of said gasket material along theskirt portion-ofthe closure to form a spaced peripheral body, ,applying pressure to said peripheral body so that thel peripheral-body is `attached to the gasket blaukrby a thin vstrip of -gasketmaterial and simultaneously pressing said peripheral body into a predetermined shape to `form argasket'wherebythe remaining gasket blank material will contract due toits memory characteristics to tear saidthin strip of-'gasketmaterial.

2. The method'of molding a sealing gasketin a closure cap, which comprises placing a gasket blank on the inside of said closure, applying pressure to `compressthe gasket blank and to force a portionrof said gasketmaterial along the skirt portion of Ythe closure to Vform a peripheral body, app-lying pressure to saidV peripheral body so that the peripheral body-.iseattached to the gasket blank by a thin'strip ofv gasket material and simultaneouslypressing said peripheralnbody into Aa predetermined shape to form a gasket whereby the remaining gasket blank material will contract due to its memory 1characteristicsv to tear said thin strip of gasket material.

3. The method of moldinga sealing gasket in a closure cap, which comprises coating Vthe inside cover of said closure with-a'compound which will prevent adherence of gasket material to metal, placing a gasket blank on the inside of said closure, applying pressure to compress the gasket blank and'to force a portion of said gasket material along the 'skirt portion'of the closure to form aV peripheral body, applying pressure to said peripheral References Cited in the le of this patent UNITED STATES PATENTS Gora Apr. 10, Stover Jan. 25, Anspon July 3, Crabtree Nov. 27, IStover Nov. 27, Stover Dec. 24, 

